THERAPEUTIC FOCUSING ULTRASOUND TRANSDUCER

Abstract

This study performed at the intersection of two areas: engineering and biomedical, which resulted in the development of a therapeutic focusing ultrasound transducer designed for the detection and non-invasive treatment of neoplasms. Main principle is emitting high-intensity ultrasonic vibrations into the focus spot (High Intensity Focused Ultrasound – HIFU). This allows to target selected areas and perform ablation of inflamed or foreign tissues without open surgery. Based on the characteristics of piezoceramic materials produced in the "Piezopribor" SCTB, mathematical modeling of the HIFU converter was performed. The basis is a piezoceramic element made in the form of a thin-walled segment of a sphere with a central hole, made of ferroelectric material PCP-35. The central hole with a diameter of 41.4 mm is designed for the imaging sensor, which acts as a" gunner" of a focused ultrasonic beam. The principle of operation of the transducer is as follows: the focal spot with the maximum acoustic pressure is located in the area captured by the ultrasound-compatible sensor. The image is transmitted to the monitor, after which a decision is made on which areas and with what intensity to influence the ultrasonic transducer. The amplitude-frequency characteristics of the converter are studied. The dependences of the active conductivity on the frequency in the free and water-loaded states are obtained. Acoustic pressure levels in the focus spot were measured. Diagrams of the radiation intensity distribution in the plane and in three-dimensional space were constructed, and work was carried out on the effect of an ultrasonic transducer on various organic materials and tissues: organic glass with a thickness of 10 mm, chicken muscle tissue. The dependences of the impact force on the power supplied to the converter, as well as the frequency of the master signal, are obtained. The possibility of using the converter as part of the HIFU therapy complex is experimentally shown. Conclusions about the prospects of using single-element focusing ultrasonic transducers and multi-element ones with a distributed focus spot are formulated.